1. Technical Field
The invention relates to a clip unit, a ligation device using the same, and a method for fabricating the clip unit.
2. Related Art
In general, a ligation device for an endoscope includes a clip unit configured to ligate a biological tissue and located at a front end of an elongated flexible sheath extending from a handle manipulation unit. The clip unit ligates a biological tissue from a desired direction by manipulating a manipulation wire inserted through the sheath to be reciprocated in the axial direction of the sheath and to be rotated around the axial direction of the sheath from the handle manipulation unit. Finally, by strongly pulling the manipulation wire to the handle manipulation side, the clip unit is detained in a body cavity in the state where the clip unit grips the biological tissue.
An example of this type of ligation device is configured to fracture a part of the clip unit when releasing the connection between the clip unit and the hook of the manipulation wire. However, since fine fragments produced due to the fracture may be scattered into the body cavity, various clip units have been proposed which are configured to release the connection by plastic deformation of the clip body or elastic deformation of the hook side (see, for example, Patent Document 1 (JP-A-2009-66226) and Patent Document 2 (JP-A-2002-360591)).
The clip disclosed in Patent Document 1 has a construction in which a hook is engaged with a claw part protruding from the base end side of the clip body which is formed by bending a plate material, and when the engagement is released, the claw part is plastically deformed. In addition, the clip disclosed in Patent Document 2 has a construction in which a hook of a slitting structure is engaged with a connection hole opened in the base end side of the clip body, and when the engagement is released, the hook is deformed by the connection hole to be disengaged from the connection hole.